28 ideas
| 1597 | Thales was the first western thinker to believe the arché was intelligible [Roochnik on Thales] |
| 17082 | Paradox: why do you analyse if you know it, and how do you analyse if you don't? [Ruben] |
| 7786 | Propositional logic handles negation, disjunction, conjunction; predicate logic adds quantifiers, predicates, relations [Girle] |
| 7798 | There are three axiom schemas for propositional logic [Girle] |
| 7799 | Proposition logic has definitions for its three operators: or, and, and identical [Girle] |
| 7797 | Axiom systems of logic contain axioms, inference rules, and definitions of proof and theorems [Girle] |
| 7794 | There are seven modalities in S4, each with its negation [Girle] |
| 7793 | ◊p → □◊p is the hallmark of S5 [Girle] |
| 7795 | S5 has just six modalities, and all strings can be reduced to those [Girle] |
| 7787 | Possible worlds logics use true-in-a-world rather than true [Girle] |
| 7788 | Modal logic has four basic modal negation equivalences [Girle] |
| 7796 | Modal logics were studied in terms of axioms, but now possible worlds semantics is added [Girle] |
| 7789 | Necessary implication is called 'strict implication'; if successful, it is called 'entailment' [Girle] |
| 7790 | If an argument is invalid, a truth tree will indicate a counter-example [Girle] |
| 7800 | Analytic truths are divided into logically and conceptually necessary [Girle] |
| 7801 | Possibilities can be logical, theoretical, physical, economic or human [Girle] |
| 3013 | Nothing is stronger than necessity, which rules everything [Thales, by Diog. Laertius] |
| 7792 | A world has 'access' to a world it generates, which is important in possible worlds semantics [Girle] |
| 17087 | The 'symmetry thesis' says explanation and prediction only differ pragmatically [Ruben] |
| 17081 | Usually explanations just involve giving information, with no reference to the act of explanation [Ruben] |
| 17092 | An explanation needs the world to have an appropriate structure [Ruben] |
| 17090 | Most explanations are just sentences, not arguments [Ruben] |
| 17094 | The causal theory of explanation neglects determinations which are not causal [Ruben] |
| 17088 | Reducing one science to another is often said to be the perfect explanation [Ruben] |
| 17089 | Facts explain facts, but only if they are conceptualised or named appropriately [Ruben] |
| 1494 | Thales said water is the first principle, perhaps from observing that food is moist [Thales, by Aristotle] |
| 1713 | Thales must have thought soul causes movement, since he thought magnets have soul [Thales, by Aristotle] |
| 1742 | Thales said the gods know our wrong thoughts as well as our evil actions [Thales, by Diog. Laertius] |